We are continuing our studies of gap junction formation in the following culture systems: Novikoff hepatoma, H35, BHK fibroblasts, endothelial cells, C6 and Y1 cells. Nucleotide transfer, ultrastructural and electrophysiological techniques will be used to investigate these systems. We will also proceed on purification of gap junctions and will attempt to produce antibodies to them. Finally, we will be studying the physiological roles of gap junctions in metabolic cooperation and regulation of proliferation.